Energy rules for new houses

GEG energy rules in Germany, explained for 2026

The Building Energy Act (GEG / Gebäudeenergiegesetz) sets the energy standard your new prefab house must meet. This guide explains the renewable-heating requirement, heat pumps, efficiency classes and how KfW funding fits in — in plain English.

See the 10-step process Quality standards (QDF & RAL)

What the GEG requires

The GEG (Gebäudeenergiegesetz, or Building Energy Act) is Germany's central law on the energy performance of buildings. It sets minimum requirements for insulation, the building envelope, heating systems and overall energy demand, and it combines several earlier laws into one framework. As of 2026 it is the rulebook every new prefab house must satisfy. The official text is available at gesetze-im-internet.de (GEG).

A defining feature of the current GEG is the push toward renewable heating. As of 2026, newly installed heating systems must draw a substantial share of their energy from renewables — commonly cited as 65%. For a new-build prefab house this typically means a heat pump or a connection to district heating rather than a fossil-fuel boiler. Because requirements are being phased in and can change, always confirm the current detail before finalising your heating.

The GEG in four points

Renewable heating

As of 2026 new heating systems must be largely renewable (commonly a 65% share), steering new builds toward heat pumps or district heating.

Heat pumps + PV

Well-insulated prefab houses suit electric heat pumps, often paired with a photovoltaic system for efficient, low-carbon heating.

Efficiency classes

Homes are rated by energy performance; many prefab houses reach an Effizienzhaus standard beyond the legal minimum. Lower numbers mean better efficiency.

KfW funding pointer

The state bank KfW offers subsidised loans/grants for efficient homes meeting defined standards. Check the current programme as of 2026.

Figures and requirements as of 2026 and without warranty; the GEG is being phased in and can change.

Efficiency classes, heat pumps and KfW funding

New homes are rated by energy performance, and many prefab houses are built to an Effizienzhaus (efficiency house) standard beyond the legal minimum. Lower Effizienzhaus numbers mean better efficiency — an Effizienzhaus 40, for example, uses far less energy than the reference building. Because prefab houses are well insulated and have low heat demand, an electric heat pump, often paired with a photovoltaic system, is a natural and efficient way to meet the renewable-heating rule.

Reaching a strong efficiency class also opens the door to public funding. The state bank KfW offers subsidised loans and, for some measures, grants for efficient new builds and renovations that meet defined efficiency-house standards. Programmes and conditions change, so as of 2026 check the current KfW offering before planning your financing. For the standards a quality German builder should meet, see our quality standards guide.

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FAQ: GEG energy rules

Answers on renewable heating, heat pumps, efficiency classes and KfW funding — as of 2026, when the rules are still being phased in.

What is the GEG (Gebäudeenergiegesetz)?

The GEG, or Gebäudeenergiegesetz (Building Energy Act), is Germany's central law on the energy performance of buildings. It sets minimum requirements for insulation, the building envelope, heating systems and overall energy demand for new and existing homes. It combines several earlier laws into one framework. As of 2026 the GEG is the rulebook your new prefab house must comply with, and it also steers heating toward renewable energy.

What are the heating rules for new houses in 2026?

As of 2026, the GEG requires that newly installed heating systems be based to a substantial degree on renewable energy — commonly a 65% renewable share. In practice this steers new-build houses toward heat pumps, connection to district heating, or other low-carbon solutions rather than conventional fossil-fuel boilers. New homes in new development areas are already subject to these requirements; the rollout for existing buildings is phased. Confirm the current detail before you plan your heating.

Are heat pumps required?

Heat pumps are not the only permitted option, but they are the most common way for a new prefab house to meet the renewable-heating requirement. Because well-insulated prefab houses have low heat demand, an electric heat pump — often combined with a photovoltaic (solar) system — is usually an efficient, cost-effective choice. Alternatives include district heating or hybrid systems, provided they meet the required renewable share. Your manufacturer can advise on the best fit.

What are efficiency classes and the Effizienzhaus standard?

New buildings receive an energy performance rating, and many prefab houses are built to an Effizienzhaus (efficiency house) standard that goes beyond the legal minimum. Lower Effizienzhaus numbers mean better efficiency — for example an Effizienzhaus 40 uses far less energy than the reference building. Reaching a strong efficiency class matters both for running costs and because it can qualify the house for public funding.

Is there KfW funding for efficient houses?

Yes. The state bank KfW offers subsidised loans and, for some measures, grants for energy-efficient new builds and renovations that meet defined efficiency-house standards. Programmes and conditions change over time, so as of 2026 you should check the current KfW offering before you plan financing. Building to a high Effizienzhaus level is usually a prerequisite for the best funding — factor this into your design and budget early.

Does the GEG make prefab houses more expensive?

Meeting modern energy standards adds cost to insulation and heating, but prefab houses are already designed for high efficiency, so many models comply comfortably. Higher upfront efficiency is offset by lower running costs and possible KfW funding. As with any figures, treat cost estimates as a guide; house prices on this site are stated excl. plot and ancillary costs, and energy upgrades should be considered in your total budget.

As of 2026, general information only, provided without warranty. The GEG and KfW programmes are being phased in and can change. Prefabricated House is an independent comparison portal; confirm current requirements and funding with your manufacturer, energy consultant and the KfW before you plan.